06/30/2026
Watch what happens when I place my finger over the port on the oil trap.
The loud squeaking noise instantly disappears. That simple test tells us this 2018 Volvo XC90 Turbo has a failed PCV valve system.
At first glance, this squeaking noise could have easily been misdiagnosed as a worn serpentine belt, belt tensioner, or pulley. Instead, the failed PCV system was creating an internal vacuum leak that produced the squeaking sound.
That same vacuum leak also allowed unmetered air into the engine, causing a lean condition and preventing the turbocharger from building proper boost, which resulted in an underboost fault.
This is a perfect example of why proper diagnostics matter. One failed component created multiple symptoms, and replacing belts or pulleys would not have fixed the problem. Taking the time to identify the root cause saves our clients time, money, and unnecessary repairs.